Cable tool drill



Jul so, 1940. E, LCO 2,209,619

CABLE TOOL DRILL 3 Sheets-Sh ee t l Char/es E. Wi/cox INVENTOR we, I Y I B% 5. x Q I/IINL ATTORN EY July 30, 1940. \MLCOX 2.209,6l9

CABLE TOOL DRILL Filed Sept. 3, 1957 5 Sheets-Sheet 2 I BY 05 y.

ATTORNEY July 30, 1940.

c. E. WILCOX CABLE TOOL DRILL Filed Sept. 3. 1937 3 Sheets-Sheet 3 m M 5 k INVEB'JTQR s dwmm/ ATTORNEY Patented July 30, 1940 Nrrso s'rATEs PATET clerics CABLE TOOL DRILL Charles E. Wilcox, Compton, Calif., assignor to Byron Jackson 00., Vernon, Calif., a corporation of Delaware Application September 3, 1937, Serial No. 162,316

Claims. (01. 255-73) This invention relates to well drilling bits of Other objects and advantages will appear from the percussion type such as are used in the drillthe following description of a preferred embodi ing of oil wells by the cable tool method. ment of the invention. I

The designs of cab-1e tool drills in general use Figure 1 of the drawings illustrates a side ele- 5 at the present time are substantially the same vation of one form of the bit in'which the en- 5* as they were 30 or 40 years ago. That is, the tire bit is one solid piece.

drills comprise a shank some 6 to feet in Figure 2 is a bottom plan view of the bit shown length provided with suitable water courses and in Fig. 1. one or more chisel-blades on the lower end of the Figure 3 is a cross section taken on line 3 3 10 shank. Such cable tool bits have several outof Fig. 1. m standing disadvantages when compared to rotary Figure 4 is a cross section taken onyline i4 bits of the type in use today. These disadvanof Fig. 1. p V tages are: (1) The tendency to deviate from Figure 5 is a vertical cross section of a bit the vertical when drilling in very hard formasimilar to that shown in Figs. 1 t0 but ii l5 tions, in steeply pitched formations, or formatwo or more pieces so that the upper cutters I6 tions having alternate hard and soft strata; (2) a e ep e and terchangeable. i very slow cutting speed; and (3) very slow and Figure 6 illustrates an alternative method of costly underreaming procedure. It is not unsecuring the cutters to bits of the type shown in common in some fields today for the drill to Fig. 5.

make only three or four feet of net hole per 24' Figure 7 illustrates a second alternative :meth- 2% hour day, due to the three factors enumerated 0d of securing the cutters to bits of the type above, even though the drill itself might be shown in Figs. 5 and 6'.

capable of digging 20 feet or more in 24 hours Figure 8- is a side elevation of one form of in this same formation. The lost time is spent underreamer bit in which the entire tool is one principally in straightening crooked hole and solid piece. p as in underreaming the hole already dug. In addi- Figure 9 is a bottom plan view of the undertion to the disadvantages enumerated above it reamer bit shown in Fig. 8. I is often impossible in caving formations, to carry Figure 10 is a cross section taken on line sumcient open hole to permit underreaming while lli-Nl of Fig. 8. g carrying the casing and it is therefore necessary Figure 11 is a cross section taken on line i I--| l 352-. to set one or more extra strings of casing. of Fig. 8. v

It is an object of the present invention to pro- Figure 12 is a'vertical cross section of an un vide a cable tool bit capable of digging straight derreamer bit similar-to that shown in Fig. .5 hole in all types of formations at a speed equal but made in two pieces so that the underreamer' 5 to or greater than present bits. cutters are replaceable and. interchangeable. Another object is to provide a cable tool bit Figure 13 illustrates the drilling bit of Fig. 1

capable of making hole much faster than present at the upper end of its stroke in a well.

bits in average formations. Figure 14 illustrates the underreamer bit of Another object is to provide an underreaming Fig. 8 at the upper end of its stroke in a well. bit which has no expanding cutters or other de- Figure 15 illustrates an alternative form of tachable parts such as are essential to present drilling bit having detachable and interchangetypes of underreamers. able reaming cutters.

Another object is to provide a combination Figure 16 illustrates a form of underreamer bit and underreamer which will underream the cutter for use with the bit shown in Fig. 15.

hole while digging it, thus permitting the casing The bits illustrated in Figs. 1 to 7, 13 and 15 45 to be carried behind the bit when digging in inclusive are for digging in open hole and comcaving formations. prise a long pilot A, having a cutting face Q Another object is to provide a combination at its lower end, a reaming cutter B at the upper tool which can be changed from a bit to "an end of the pilot,- and the usual wrench square underreaming bit by replacing or removing a C, collar D and threaded pin E. The bit is 5 0 portion of the cutters. threadedly attached to a drilling stem F in the Another object is to provide a combination usual manner. The pilot cutter may be of any tool which can be adapted to various sizes of well known type such as a flat chisel blade hole by changing only a part of the bit cutters (regular or Mother Hubbard bit), a. spiral or underreaming cutters. bit or a star bit such as is shown in the :draw- 55 ings. The four bladed star bit is preferable because it tends to drill straighter hole. The pilot cutter should be long enough so that it does not come out of the pilot hole H while digging. Since the length of the drilling stroke is variable the length of the pilot may be varied but should always be as long or longer than the stroke. A pilot of 8 feet to 15 feet in length has been found suitable for general use. The diameter of the pilot cutter is substantially less than the diameter of the hole to be cut.

may have pilot cutters of say twelve to ten inches in diameter. 10 inch and 8 inch bits may have a pilot seven inches in diameter. Thus it may be said that the length of the pilot cutter is approximately 10 to 20 times the diameter thereof, but is preferably about 15 times the diameter.

The reaming cutters B may be of any well known type and should be of such a diameter, with respect to the diameter of the pilot cutter and the hole, that the reamer and pilot cutters out approximately equal areas. The reaming cutters B are positioned some 8 to 15 feet above the cutting face of the pilot A. Water courses P of any well known type may be provided.

The reaming cutters B are preferably formed with a slightly concave under surface, that is, they slope upwardly and inwardly toward the vertical axis of the bit. This protects the inner edge G of the shoulder of the pilot hole H (Fig. 13) from crumbling. The cutters B are preferably provided With several short radial cutting teeth 0.

It is desirable to keep the pilot cutter A as small in diameter as possible because a small cutter penetrates a hard formation more easily than a large cutter and is less likely to deviate from the vertical. For this reason and the fact that the pilot and reamer cutters should cut approximately equal areas, it is advisable, when making large diameter hole (such as a 20 inch hole) to provide a relatively small diameter pilot and two or more sets of reaming cutters, one above the other, adapted to ream the hole in two substantially equal steps, each step cutting an area approximately equal to the pilot cutter. These reaming cutters may be integral with the cutter body B or may be separate, detachable and interchangeable pieces such as are illustrated in Figs. 5 to 7, and 15 inclusive. Different combinations of pilot and reamer cutters can be used if desired.

Fig. 5 illustrates a pilot A| and two sets of reamer cutter subs I and J detachably connected together by means of the usual threaded pin and box construction. The cutters are preferably located above the threaded box portion of the sub so that the threads will not be damaged by heat when the cutters are dressed.

Fig. 6 illustrates a bit in which the pilot A2 is integral with the upper reamer cutter Bl, the upper end of the pilot being enlarged and threaded as shown at K to receive a threaded sleeve L which forms the lower reamer cutter. The sleeve L is shouldered against the under side of the reamer body as indicated at N torelieve the threads K of the upward thrust of the reamer sleeve L. The upper portion of the pilot adjacent the reamer cutters is preferably made cylindrical and not threaded so that heat will not harm the threads when the reamer cutters are dressed.

For example, bits. having diameters of from 20 inches to 12 inches Fig. 7 illustrates a modification of Figs. 5 and 6 in which the pilot A--3 is detachable and the lower reamer cutter L-l is a sleeve as in Fig. 6 but instead of being threadedly connected to the shank it is held in place between the upper shoulder of the pilot A3 and the lower shoulder of the upper reamer cutter 3-2.

The construction described provides a bit which will dig rapidly because the pilot is of relative small diameter and penetrates the formation easily, while the reaming cutters have only to break down the upper edge and corner of the pilot hole, which is easier to do than to drill a full diameter hole of the same size. Moreover, the long pilot and stabilizing reamer cutters keep the bit on the vertical so that the operator can give the bit more weight than would otherwise be the case, thus speeding up the drilling rate even more without danger of making crooked hole.

The bit tends to stay on the vertical because the reamer cutters are dressed out to the full hole diameter and are located a substantial distance (10 to 2,0 diameters) above the cutting face of the pilot. This construction also eliminates tight hole because the cutting edges of the bit and reamer are dressed out a substantial distance from the shank of the bit.

The operation of the bit is similar to that of any conventional cable tool bit.

Figs. 8 to 11 illustrate a bit similar in most respects to the bit shown in Fig. 1 but adapted to underream at the same time that it makes new hole. The pilot cutter A-4 is similar to the pilot A of the bit shown in Fig. 1. The underreamer cutter R is somewhat like the reamer cutter B but is located on only one side of the pilot A-4, that is, the underreamer cutter is eccentric with respect to the vertical axis of the pilot cutter and the pin collar D2. As shown in Fig. 9, the radius V of the underreamer cutter is preferably less than the radius W of the hole to be cut but greater than the radius X of the pilot cutter. Thus, when the pilot is reciprocated in the pilot hole while being rotated in the usual manner, the underreamer cutter R cuts a circular hole, the center of which is the vertical axis of the pilot A4. As illustrated in Fig. 14, the well casing S is carried in the hole some 15 or 20 feet above the bottom of the hole and is lowered from time to time as the bit makes progress. A drill stem F-2 is secured to the upper end of the underreamer bit and extends upwardly into the casing S a short distance. Inasmuch as the underreamer cutter R is eccentric with respect to the well it does not serve as a guide to the same extent as does the reamer cutter B of Fig. 1. Therefore, it is preferable to provide an eccentric stabilizing guide cutter M a short distance below the eccentric cutter R. and on the opposite side of the bit body from the cutter R. The cutter M cuts on the same (or a slightly larger) diameter as the pilot cutters and because the cutter is, in use, always dressed out to approximately its full gauge, it serves as a stabilizer at the top of the pilot hole tending to keep the bit on its vertical axis. It is sometimes desirable to provide a guide or stabilizer T on the upper end of the stem F-2 to keep the upper end of the bit centralized in the well. The guide T may be of any of the well known shapes and sizes such as are commonly used for this purpose. While drilling, the guide T should not drop below the lower end of the casing.

The underreamer cutter R may be provided with exterior fluid channels Pl as shown in Fig. 1 or it may be provided with one or more longitudinal holes U. The advantage of the holes U is that they permit all of the periphery of the cutter to be utilized for cutting.

Figure 12 illustrates a modification of l the underreamer bit of Fig. 8 in which the underreamer cutter R-l is detachable and interchangeable with respect to the pilot cutter A-5. In the present instance the members R,I and A5 are shown as being connected together by means of a threaded pin and box connection, although other constructions could be used. In the preferred embodiment the underreamer body is provided at its lower end with a stabilizing cutter M-I opposite and somewhat below the reamer cutter R-I.

The underreamer bit described above has no expanding parts, can be run through casing like an expanding underreamer, will cut a hole as large or larger than conventional underreamers, has a greater cutting area on the underreamer cutter than conventional underreamers, and because of the long pilot cutter it tends to make straight hole at all times.

With this underreamer bit the casing can be carried close behind the bit with very little open hole. In many instances this will result in the saving of one or more strings of casing.

The bit saves a great deal of time where underreaming is required because it underreams as it digs and does this as fast or faster than a conventional type of bit will make open hole which must then be underreamed.

The operation of the underreamer bit is similar to that of the reamer pilot bit or any conventional cable tool bit.

Figures 15 and 16 illustrate a combination bit and underreaming bit somewhat like the tool shown in Fig.6 but adapted to be used either as a bit (having interchangeable cutters L2 oi the threaded sleeve type), see Fig. 15, or as an underrearning bit (Fig. 16) having interchangeable eccentric reamer cutters of the threaded sleeve type L-3. The sleeve L--3 is preferably, though not necessarily, provided with a stabilizing cutter L-4 positioned opposite the reamer cutter L3 and somewhat below same. The stabilizing cutter L4 preferably cuts on the same radius as the pilot cutter Q-5 although it may cut on a slightly larger radius if desired. The reamer cutter sleeves L2 and L-3 are adapted to seat against a shoulder N2 on the pilot body A-B to relieve the threads of the shock load. The pilot A6 unlike the pilot A-2 of Fig. 6 has no integral reaming cutters Bl, otherwise it could not be used interchangeably as a bit or underreamer bit. The advantage of this construction is that a single pilot can be used with a considerable number of difi'erent sizes of reamer or underreamer cutters, thus permitting a considerable saving in tool investment.

Iclaim:

1. A cable tool pilot bit comprising a pilot cutter having a diameter substantially smaller than the diameter of the holeto be cut, an underreamer cutter above said pilot cutter and eccentric to the vertical axis thereof and a stabilizer adjacent the upper end of said pilot cutter and below said underreamer cutter, said stabilizer being eccentric to the vertical axis of the bit and located on the diametrically opposite side thereof from the portion of maximum eccentricity of said underreamer cutter and extending outwardly from said pilot cutter a distance substantially less than said underreamer cutter.

2. A cable tool pilot bit as defined in claim 1 in which the underreamer cutter is substantially annular in shape extending around the axis of said bit approximately 180 degrees.

3. A cable 'tool drilling bit comprising a pilot cutter having a diameter substantially smaller than the diameter of the hole to be cut, the upper portion of said pilot cutter being enlarged and threaded, andan eccentricunderreamer cutter comprising a sleeve threaded internally and adapted to be mounted on said pilot cutter, said eccentric underreamer cutter having a cutting surface at only one side thereof, the radius of said cutting surface being less than the radius of the hole to be cut.

4. A cable tool drilling bit comprising a pilot cutter having a diameter substantially smaller than the diameter of the hole to be cut, the upper portion of said pilot cutter being threaded, and an eccentric underreamer mounted on said threaded portion, said underreamer comprising a sleeve threaded internally, an underreamer cutter disposed at one side of said sleeve and having a cutting radius less than the radius of the hole to be cut but being offset laterally of the vertical axis of said pilot cutter a distance such that the outermost edge of said underreamer cutter is at the edge of the hole to be cut, and a stabilizing cutter on said underreamer positioned opposite and below said underreamer cutter, said stabilizer cutter being adapted to cut on approximately the same radius as said pilot cutter.

5. A cable tool drilling bit comprising a pilot cutter having a diameter substantially smaller than the diameter of the hole to be cut, an eccentric reaming cutter positioned above said pilot cutter and offset laterally of the vertical axis. of

said pilot cutter, and a stabilizing cutter positioned at the upper end of said pilot cutter at the opposite side to said reaming cutter and below said reaming cutter, said stabilizing cutter having an effective cutting radius at least as great as that of said pilot cutter.

CHARLES E. WILCOX. 

